This invention is similar to the normal tractor mounted post hole digger but differs in several commercially important aspects. The earth drill of this invention will drill post holes but also is designed with a low profile to drill holes in an area with restricted headroom. Further, the design incorporates an extensible auger that allows drilling holes to greater than six foot depths. Special drills equipped with rock bits are also used in this design since locking features to allow using the tractor weight to put downward pressure on the drill are included. Most importantly all moving parts are guarded and the unit is equipped with an automatic overload trip to not only improve personnel safety but also to allow drilling holes directly under a somewhat moveable obstruction such as a fence by using the auger guard to hold the obstruction temporarily out of the way.
The low profile is obtained using two commercially available hydraulic cylinders fastened side by side and moveable within a channel in the unit housing to pressure the auger downward and to lift the auger out of a hole.
We have considered the following patents:
______________________________________ Document No. Name Date ______________________________________ 3,700,045 John G. Coontz 10/24/72 2,939,682 Paul J. Kromberg 01/08/58 2,662,736 W. A. Abrams 02/19/52 2,639,892 Glenn H. Jones 05/26/53 2,774,568 Glenn H. Jones 12/18/56 ______________________________________